Due to the large dimensions and weight of wind turbines, the load bearing capabilities and performance of the bearing arrangement supporting the rotor shaft and wind turbine blades is of high importance. Typically, for a wind turbine of horizontal, or near horizontal, rotor shaft type, the bearing arrangement must support both axial and radial loads, wherein the axial loads commonly comprises axial loads transferred from the turbine blades during operation as well as axial loads arising from the weight of the rotor shaft and turbine blade arrangement which is commonly mounted with a tilted angle in relation to the horizontal plane in order to reduce the risk of collision between the turbine blades and the wind turbine tower. Also, the weight and size of the components as well as the location of the rotor arrangement in tower like structures increase the cost for replacement and servicing, if required.
Known bearing arrangements for supporting a given radial and axial load characteristic of a wind turbine rotor shaft, however, require high manufacturing precision of the bearings raceways and raceway-contacting surfaces of the rolling elements, as well as high precision of the alignment between the rotor shaft and bearing housings structures at different support points along the axis of the rotor shaft. Furthermore, complex roller raceway geometries comprising e.g. roller guiding sleeves increase the precision and alignment requirements of the bearings, as well as increasing the mass and cost of material of the complete wind turbine arrangement. Also, in order to provide suitable axial location function, the required axial and radial extension of known rolling bearing solutions increase the space requirements and the overall size and weight of the wind turbine nacelle framing.